In the production of glass containers, such as bottles, jars, etc., in an automatic machine of the I.S. type, molten glass in the form of gobs is fed and distributed by means of a distributor, to the individual forming sections (generally eight) where the glass is shaped into a container.
The containers formed by each of the individual forming sections of the machine, while still hot, are deposited first on the dead plate of the respective section and from there they are pushed up to a transfer conveyor called a "carrier" which moves the containers of all of sections up to a "transfer" placed at the end of the carrier. The transfer regulates the movement of the containers separating them uniformly and changing their direction of travel by 90.degree., and deposits them one by one, uniformly spaced in a row, on a cross conveyor. Once a complete row is formed, a transfer device or mechanical pusher, simultaneously transfers all the containers from the cross conveyor to the lineal conveyor of a lehr, wherein they are exposed to a tempering process which eliminates the residual stresses accumulated in the glass due to fast cooling during the fabrication process.
Pusher devices of the prior art generally consist of a pusher rod which pushes the bottles or articles advancing in a row on the cross conveyor, to the edge of the lehr belt. The movements of the pusher rod and the "transfer" are synchronized to coordinate the operation of loading glass articles into the lehrs. The pusher rod is generally coupled to a frame which transmits movements of pushing, elevation and return, for each row of bottles formed on the cross conveyor.
An example of known pusher apparatus may be found in U.S. Pat. No. 3,040,867 of June 26, 1962. In this patent, a transfer mechanism placed adjacent the cross conveyor and generally aligned with the lehr conveyor, simultaneously transfers a plurality of articles from the cross conveyor to the lehr conveyor. Movement of the pusher is first perpendicular to the cross conveyor to make contact with the articles, then diagonally in the general direction of movement of the cross conveyor in order to avoid the next row of containers and then longitudinally of the lehr conveyor.
U.S. Pat. No. 3,184,031 of May 18, 1965 describes a pusher apparatus of the type which pushes or transfers the bottles in a diagonal path relative to the motion of the cross conveyor, until transferring the bottles at the entrance of a lehr. The pusher bar is then elevated and retracted after the bottles have been pushed to a position behind the next row of bottles formed over the cross conveyor and then lowered to begin a new transfer cycle. The pusher of this patent comprises fundamentally a transfer mechanism which includes one cam for controlling the upward and downward movements of the pusher rods and another cam which controls the advance and return movement of the pusher rod. Both cam movements are controlled by independent drive mechanisms and are synchronized to the pusher rod to follow a predetermined path.
In U.S. Pat. No. 3,960,266 of June 1, 1976, a pusher apparatus is described which transfers the bottles simultaneously from a position where they travel on the cross conveyor in a given direction, to another position where they travel on the lehr conveyor at a slower speed in another direction transverse to the first by means of an angular movement of 90.degree. of the pusher apparatus. This transfer sequence is imparted by a crank in the drive shaft which through a connecting rod causes an oscillatory motion through 90.degree. of a pivoted arm.
Finally in U.S. Pat. No. 4,067,434 of Jan. 10, 1978, a pusher is described of the type that pushes a row of glass containers from the cross conveyor to a transition dead plate and from the dead plate to a lineal conveyor of the lehr. The pusher apparatus of this patent is generally constituted by a fixed base having in its upper part a support frame which is positioned opposite to the entrance of the lehr. The support frame comprises a transfer mechanism to transfer simultaneously a plurality of articles in a transfer path by means of both lateral and forward movement. The pusher apparatus of this patent has a stabilizing rod mounted in the transfer mechanism, which is placed beyond the container rows and advances and returns together with the pusher rod preventing the containers from falling forward or backward while they are moved from the cross conveyor to the lehr conveyor. Up to now, this type of pusher has been considered to be the most functional because 90% of the bottlesproduced are conveyed in the range of velocities that can be handled. Nevertheless, the introduction of faster mechanisms such as the I.S. machine of eight sections and greater production output will require handling a greater quantity of articles in a smoother and faster way without causing the articles to fall during the pushing transfer. In practically all the pusher apparatus in use today, the motion of the pusher rod is imparted by means of cams and bar mechanisms which generate a pushing stroke which takes a shorter time than the time of the return stroke. For this reason, it is practically impossible to achieve greater operation velocities of the pushers because the excessive velocity of pushing causes the articles to fall resulting in a reduced output of the finished product. The inventors here, however, have discovered that because no articles are handled during their return stroke of the pusher, it is not imparative to follow a smooth path during the return stroke. Therefore, it is possible to increase the total time of the pushing stroke while decreasing the time of the return stroke and as a result the smoothness of the pushing stroke is increased and therefore allowed a greater operating velocity of the overall machine. This is achieved by means of a quick return mechanism positioned between the cam and the drive means in such a way that the stroke angle of the drive means during the pushing path is greater than the corresponding angle during the return path.